Phased array wireless resonant power delivery system

ABSTRACT

A resonant power transmission system for wirelessly delivering electric power to a target device. A transmitter resonant phased array includes a power source operable to source alternating current power at a target frequency. A plurality of transmitting elements, each operable to produce a non-radiated magnetic field, produces a composite non-radiated magnetic field. A plurality of transmitter tuned circuit elements couple the alternating current power to the plurality of transmitting elements. Control circuitry controls the plurality of transmitter tuned circuit elements to direct the composite non-radiated magnetic field toward the target device. Communication circuitry communicates with the target device. The plurality of transmitting elements may be a plurality of coils with the control circuitry individually controlling phase of the non-radiated magnetic fields produced by the plurality of transmitting elements by control of the plurality of transmitter tuned circuit elements. The plurality of coils may be directed mechanically in other embodiments.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS ContinuationPriority Claim, 35 U.S.C. §120

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. §120, as a continuation, to U.S. Utility Patent ApplicationSer. No. 12/241,279, entitled “Phased Array Wireless Resonant PowerDelivery System,” filed Sep. 30, 2008, which will issue as U.S. Pat. No.7,893,564, on Feb. 22, 2011 (Attorney Docket No. BP7195), whichapplication claims priority under 35 U.S.C. 119(e) to U.S. ProvisionalApplication Ser. No. 61/086,387, filed Aug. 5, 2008, which are herebyincorporated herein by reference in their entirety and made part of thepresent U.S. Utility Patent Application for all purposes.

BACKGROUND

1. Technical Field

The present invention relates generally to the wireless charging of abattery powered device; and more particularly to techniques for nearfield wireless resonance power delivery to a target device.

2. Related Art

All electronic devices require electrical power to operate. Mobiledevices such as laptop computers and cell phones typically include arechargeable battery that is recharged when the device is plugged into apower socket. Rechargeable batteries must be charged from wall powerregularly to maintain battery life because rechargeable batteriesdischarge even when not used. The users of the mobile devices oftensuffer due to inaccessibility of electrical power for battery charging.In such a situation, the user must carry multiple batteries forcontinued operation of the mobile device. Requiring a user to carrybackup batteries not only incurs the expense of the additional batterybut requires transport space and increased transport expense.

Users of mobile devices usually carry power cables so that they canrecharge the batteries of their mobile devices. These power cables areoften misplaced or lost, inconveniencing the users. Quite often, thepower cables are device specific and cannot be used in place of oneanother. Further, even with a power cable in hand, power sockets may beunavailable. This problem is a particular issue in airports or otherpublic places, which users of the mobile devices frequent. In somecritical applications, such as military applications and medicalapplications, it becomes a dangerous if not disastrous to interfere withan ongoing activity/communication of a mobile device simply to rechargethe device's battery.

Near field power delivery has been known for many years. Nikola Teslafirst experimented with such power delivery many years ago, although hissolutions were not viable for various reasons. Near field power deliverytypically exploits magnetically coupled resonance, which allows twoobjects resonating at the same frequency to exchange energy withmoderate efficiency. The frequency of such near field resonance may bemuch lower than wireless communication frequencies, e.g., 10 MHz fornear field resonances compared to 2 GHz for wireless communications.Thus, near field power delivery shows much promise, although it is notyet commercially exploited.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of ordinary skill in the artthrough comparison of such systems with the present invention.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theDrawings, the Detailed Description of the Invention, and the claims.Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a resonant power transmissionsystem that wirelessly delivers power to a target device in accordancewith one or more embodiments of the present invention;

FIG. 2 is a block diagram illustrating an array of coils focusing theirmagnetic field lines to a target device location in accordance with oneor more embodiments of the present invention;

FIG. 3 is a block diagram of illustrating a portion of the phased arrayresonant power transmission system of FIG. 1 that is operable tocalculate the location of the target device based on the receivedinformation to direct a magnetic field pattern in accordance with one ormore embodiments of the present invention;

FIG. 4 is a perspective diagram illustrating approximate orientations ofmagnetic fields produced by a phased array resonant power transmissionsystem the resonant coil in the resonant power transmission system andthe receiver resonant phased array magnetically coupled showing thelinking magnetic field lines during the resonant power delivery inaccordance with one or more embodiments of the present invention;

FIG. 5 is a block diagram illustrating a receiver resonant phased arrayconnected to (or incorporated with) a target device with each of aplurality of tuned circuits having a coil and a capacitor resonating ata coupled magnetic field frequency in accordance with one or moreembodiments of the present invention;

FIG. 6 is an illustration of superposition of two signals from twoseparate tuned circuits of the receiver resonant phased array; a similarsuperposition or a spatial constructive magnetic field interference (asvector addition) takes place at the magnetic focal point in accordancewith one or more embodiments of the present invention;

FIG. 7 is the system diagram illustrating automatic tripping componentsof a resonant power transmission system when a living body or a movingobject receives a coupling magnetic field in accordance with one or moreembodiments of the present invention;

FIG. 8 is a flowchart illustrating operations performed by the resonantpower transmission system of FIG. 1 during resonant power deliveryoperations in accordance with one or more embodiments of the presentinvention; and

FIG. 9 is a flowchart illustrating operations performed by a powerdelivery controller of the resonant power transmission system of FIG. 1when a moving object interferes on the path of the resonant magneticpattern in accordance with one or more embodiments of the presentinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention address battery power chargingin-situ from a remote power source (station) wirelessly usingradiated/magnetic power or non-radiated magnetic fields. This approachof recharging a battery in remote devices is applicable to fairly longdistance between a power source and a target device i.e., a portableelectronic target device having rechargeable battery. In someembodiments of the present invention the delivery of power is conductedthrough relatively high frequency resonant magnetic coupling between apower source and a target device, the target device being an electronicdevice that runs on a portable rechargeable battery embedded in it. Suchhigh frequency coupling is magnetic coupling in some embodiments but maybe Radio Frequency (RF) coupling in other embodiments. Such coupling maybe described herein as wireless power transfer, beam forming, RFbeaming, or other beaming/power delivery. In typical embodiments of thepresent invention for wireless power transfer, the power source and thetarget device are tuned to the same frequency. Such tuning results inmagnetic resonance in the target device for power transmitted by thepower source, with air as the medium for power transfer.

In accordance with some embodiments of the present invention, themagnetic coupling is directed towards the target device by properlyshaping a controllable magnetic generating coil array/antenna array thatis powered by an alternating current power source. This system works ona transformer principle but with an air core and coupling across adistance. For example, the system of the present invention may use oneor more coils disposed in a floor or ceiling of a room with targetdevices within the room receiving power. However, coils of the presentinvention could be disposed in a structure such as a kiosk in a shoppingmall or airport, with an operator of the kiosk charging target devicesfor being charged at the kiosk. Various other installations of thedevice may be employed according to the teachings described herein.

Magnetic signals/fields created by the power source are received by anantenna/coil of the target device. The received signals/fields chargecapacitors through diodes at the target device. An array of suchcapacitors may be connected in series using a plurality of diodes. Thisarray of capacitors and plurality of diodes helps in rectification of AC(alternating current) to DC (direct current) and may amplifying the DCvoltage to a value that is sufficient to charge a battery in the targetdevice. A power/voltage sensing mechanism of the target device helps tocontrol the power/voltage of the signal used to charge the battery, inaccordance with the present invention. A low voltage limit/low powerlevel sensing circuitry in the target device initiates a power requestto the power source (sometimes referred to as a wireless power stationor resonant power transmission system). A high voltage limit/high powerlevel sensing circuit senses the maximum allowable battery voltage orpower level during charging. Once the battery is charged to a maximumlevel, the high voltage sensing circuitry initiates a termination ofpower delivery, such as by communicating a request for the resonantpower transmission system (power station) to cutoff the power, byterminating the wireless transmission of magnetic fields (radiated ornon-radiated, as the case may be)/magnetic resonant power transmissions.

Authorization module(s) of the target device and the resonant powertransmission system communicate to authenticate the target device forreceipt of resonant power from the resonant power transmission system.For example, such authentication is done based on the information thatthe authorization module shares with the resonant power transmissionsystem. Specifically, in one embodiment, the authentication is conductedbased on the comparison of authentication information sent by theauthorization module with other information available in anauthentication database in the resonant power transmission system.

According to an aspect of the present invention, the resonant powertransmission system and the target device communicate with one anothervia the power delivery signal. These communications may includeinformation relating to the power charging or other information. Becauseof the strong wireless coupling between the resonant power transmissionsystem and the target device, high data rate communications may besupported by using this technique. For communications from the targetdevice to the resonant power transmission system, the same principle maybe employed. However, in some embodiments, communications between thetarget device and the resonant power transmission system may besupported by other wireless techniques such as Wireless Local AreaNetwork (WLAN) operations, e.g., IEEE 802.11x, Wireless Personal AreaNetwork operations (WPAN) operations, e.g., Bluetooth, infraredcommunications, cellular communications and/or other techniques.

In accordance with the present invention the efficiency of the powerdelivery is further enhanced using a plurality of resonating coilsarranged in the form of an array called the transmitter resonant phasedarray. Each of the coils of the resonating circuit is associated with acapacitor for the resonant action. The combination of the coil andcapacitor forms tuned circuit that can be tuned to the frequency of acontrolled power source. The controlled power source of the presentinvention is the power source used to generate the coupling magneticfield pattern in the space that couples the resonant power transmissionsystem and the target device magnetically.

The signal from the controlled power source of the present invention isdivided among number of ports, equally. The power from the output ofthese ports is fed to the plurality of the tuned circuits of thetransmitter resonant phased array. The number of ports in the powerdivider is equal to the number of tuned circuits in the transmitterresonant phased array. In accordance with the present invention thephase of the signal fed to each of the tuned circuits is adjusted tocompensate for the phase difference among the phases of the signal fedto the plurality of the tuned circuits. This phase compensation isrequired to account for the path difference of the signal on the wiresand the path in free space.

Further the coils of the tuned circuit can be orientated in space todirect their induced magnetic field in the required direction inaccordance with the present invention. This is done using a directionalcontroller in the resonant power transmission system. This helps tofocus the magnetic field pattern to a single point in space called thefocal point. The magnetic field line from different tuned circuit addsvectorially maximizing the field at the focal point. On the targetdevice side the receiving of the power is accomplished using a receiverthat may include a resonant phased array having similar tuned circuitsas on the transmitter resonant phased array.

In the process of the phasor addition the phase of the each of thereceived voltages may be compensated so that all the induced voltageshave the same amplitude, frequency, and phase. During the phasecompensation process the phase of the voltage across the coil from thecenter of the receiver resonant phased array may be considered as thereference phase. The process of combining the power content of each ofthe phase compensated voltages results in high efficiency of the powertransmission. The combined power is used for the target device batteryrecharging.

In accordance with another embodiment of the present invention a safetymechanism is built into the power delivery system to cutoff the powerdelivery when a living/moving object interferes with the power deliverypath close to the focal point. The power delivery process is resumedafter an arbitrary small amount of time sensing the exit of theliving/moving object from the path of the power delivery.

FIG. 1 is a block diagram illustrating a resonant power transmissionsystem that wirelessly delivers power to a target device in accordancewith one or more embodiments of the present invention. The resonantpower transmission system 103 sends a beacon signal at regular intervalon a communication channel 149, particularly target device 129. Inresponse to the beacon signal the target device 129 sends a request forwireless power delivery. The resonant power transmission system 103identifies the target device, authenticates the target device for powerdelivery, and wirelessly delivers power to the target device 129 whenthe target device is authenticated. After power delivery commences, thedelivery is constantly monitored in closed loop. The closed loopoperation ensures power delivery operation at an optimum coupling, rightpower level, and at a right frequency. Any deviations in theseparameters are communicated by target device 129 to the resonant powertransmission system 103 and alteration in operation may be commenced.

The resonant power transmission system 103 includes a transmitterresonant phased array 105 and a communication circuit 115 and isoperable to wirelessly deliver electric power to the target device 129and to communicate with the target device 129. The transmitter resonantphased array 105 includes a controlled power source 113, a plurality oftransmitting elements, a plurality of transmitter tuned circuitelements, and control circuitry. The power source, embodied as acontrolled power source 113 in FIG. 1, is operable to source alternatingcurrent power at a target frequency. The plurality of transmittingelements, included in the transmitter tuned circuit array 107 of FIG. 1,are each operable to produce a non-radiated magnetic field with theplurality of transmitting elements operable to produce a compositenon-radiated magnetic field 147. The plurality of transmitter tunedcircuit elements, also included in the transmitter tuned circuit array107 of FIG. 1, are operable to couple the alternating current power tothe plurality of transmitting elements. The control circuitry, embodiedas directional controller 109 and/or phase controller 111 of FIG. 1, areoperable to control the transmitter tuned circuit array to direct thecomposite non-radiated magnetic field 147 toward the target device 149.

In some embodiments, as will be illustrated further in the FIGS. anddescribed further with reference thereto may include a plurality ofcoils. In such embodiments, the control circuitry (phase controller 111)is operable to control the plurality of tuned circuit elements toindividually control phase of the non-radiated magnetic fields producedby the plurality of transmitting elements to control directionality ofthe composite non-radiated magnetic field 147 by controlling phase ofsuch non-radiated magnetic fields. The control circuitry is operable toreceive feedback from the target device 129 via the communicationcircuitry 115 that is used to direct the composite non-radiated magneticfield 147. In some embodiments, the plurality of tuned circuit elementscomprise lumped circuit elements whose elemental values are controllablyvaried by the control circuitry to control phase of the non-radiatedmagnetic fields produced by the plurality of transmitting elements.

As will be described further with reference to FIG. 2, the plurality oftransmitting elements may be arranged in an array. This array may beconfigured any many differing manners. For example, if the array ismounted in a ceiling or floor, the array may be parallel to the ceilingor floor so that the non-radiated magnetic fields are directed toward aroom below (or above). With the array mounted in a kiosk or otherstructure, the array may be mounted so that the non-radiated magneticfields are directed towards an area in which target devices are locatedthat will receive power. In some embodiments, the array is mechanicallyactuated with the resonant power transmission system further including adirectional controller for physically controlling orientation of theplurality of transmitting elements (coils, antennas, etc.). The controlcircuitry may be further operable to dynamically select the targetfrequency.

The transmitter tuned circuit array 107 may consist of an array of tunedcircuits that are controllable. Each of the tuned circuits may be acombination of a coil and a capacitor. The resonating action of thetuned circuit maximizes directional coupling with the target device. Thedirectional controller may 109 orient the energy produced by coils ofthe tuned circuits so that the composite field is directed toward acommon point of a target device 129 location called “the magnetic focalpoint.” At the magnetic focal point the coupling field becomes amaximum. The magnetic field setup by the plurality of the coils by theresonant action is called the resonant field pattern. In someembodiments, the directionality of the coils is physical, i.e., they maybe directed via physical means. In other embodiments, the physicalposition of the coils is fixed.

The phase controller 111 has the functionality of controlling the phaseof the field pattern from each of the coils fed to a magnetic focalpoint. The phase adjustments are done for accounting the path differenceexperienced by different tuned circuit field patterns in reaching themagnetic focal point. This will ensure constructive interference of themagnetic field components from different tuned circuits (or coils) atthe magnetic focal point.

The phase controller 111 may execute an optimizer algorithm based uponfeedback from the target device 129 that may be based on the receivedpower level of the target device 129. The power level informationreceived by the resonant power transmission system 103 triggers theexecution of the algorithm to maximize the magnetic field pattern at themagnetic focal point, which will be communicated by the target device tothe resonant power transmission system 103.

During the magnetic field pattern maximization algorithm execution thephase controller 111 is controlled in such a way that it keeps adjustingthe signal phase in a progressive steps in either positive or negativedirection to compensate for the path difference. The central coilelement of the array is considered as the reference for the phasecontrol with respect which each signal phases from other coils areadjusted. The direction of the phase adjustment is done based on therelative position of the coil in the array and also based on theposition of the magnetic focal point in the space.

Another parameter of interest to control is the power level. Aftermaximizing the magnetic field intensity at the magnetic focal point withrespect to phase difference and direction, the field intensity can befurther varied by the power level variation of the controlled powersource 113. The power from the controlled power source 113 is fed to apower divider diving power equally into many ports with number of portsequal to the number of the coils. The power level for each of the tunedcircuit is adjusted by a plurality of the power amplifiers providing therequired power gain.

The magnetic fields due to a plurality of the resonant coils aresuperimposed in the space whose phases are adjusted for a constructiveinterference. The field pattern at the magnetic focal point is calledthe resonant magnetic pattern in accordance with the present invention.

The communication circuit 115 has a parameter receiver 117, beaconmodule 125, and target device authentication module 127. Thecommunication circuit 115 does the coordinating and feedbackfunctionality between resonant power transmission system 103 and atarget device 129.

The coordinating functionality includes the sending of the beaconsignal, exchange of the authentication information, power request,target device location information, billing information, etc. Thefeedback information includes the receiving of target device receivedpower level, frequency, charging time, etc. The coordination informationand the feedback information are exchanged on a separate (common)channel 149. The power delivery is done on a separate channel 147 in theform of magnetic field coupling with the receiver resonant phased array145. The receiver resonant phased array is connected with the targetdevice 129. The received power is delivered to the target device 129using a power cord 151. The channel 147 setups a resonant magnetic fieldpattern directed in the direction of the target device 129.

The parameter receiver 117 of the communication circuit 115 receivesfeedback from the target device 129. The feedback parameters of interestare power, frequency, charging status, and authentication information.

The frequency selection receiver 119 of the communication circuit 115receives the frequency information from the target device 129 beingtuned to. The power level receiver 121 receives the received power levelby the target device 129. The received power level helps in transmitterresonant phased array coil orientation direction adjustment.

The charging status receiver 122 receives the charge status of therechargeable battery within the target device 129. The target devicelocation receiver 123 receives the target device 129 location in GPScoordinates at the regular time interval. If the target device ismobile, this is required to continuously track and transmits itslocation information.

The beacon module 125 continuously transmits the beacon signalindicative of the resonant power availability. In response to the beaconsignal a target device will send power request signal and subsequentauthentication. The target device authentication module 127authenticates the power request made by the target device 129.

The receiver resonant phased array 145 is the part attached with thetarget device 129 using a power cord 151 or that is incorporated withthe target device 129. The receiver resonant phased array (“RRPA”) 145receives the power from the magnetic field coupling. The components of145 are described in FIG. 5. In receiving the power the coils of theRRPA 145 are tuned to resonate with the coupling resonant magneticfield.

The target device 129 is for e.g. a cell phone or a laptop computerhaving a power charging circuit 131, a user authentication module 135, afrequency sensor 137, a power level sensor 139, a location finder 141,and a target device communication circuit 143.

The power charging circuit 131 receives the power from the receiverresonant phased array 145 via the power cord 151 and converts into aform suitable for battery charging. It has the battery charging circuit132 and a rechargeable battery 133. The battery charging circuit 132converts the incoming power into DC (direct current) suitable forcharging the rechargeable battery 133. The rechargeable battery 133 isthe powering source for the entire operation of the target device 129.

The user authentication module 135 exchanges the target device identityand authentication information. For e.g. the user authentication module135 in one embodiment can be a SIM card based identity provider.

The frequency sensor 137 senses the frequency of the coupling magneticfield pattern and sends it on the channel 149 to the resonant powertransmission system 103. The power level sensor 139 senses the receivedcharging power level by the target device 129 from the receiver resonantphased array 145. The location finder 141 sends the target devicelocation to the resonant power transmission system 103.

The power level, frequency and location information are continuouslytransmitted from the target device 129 to the resonant powertransmission system 103. This information is used by the directioncontroller 109 for positioning the magnetic focal point, by controllingthe orientation of the coils, by phase controlling, and by the powerlevel controlling. This is performed using the direction controller 109,power controller 111, and the controlled power source 113 respectively.These three modules control the respective parameters appropriately tomaximize the coupled resonant magnetic field at the target devicelocation or the magnetic focal point.

The target device communication circuit/module 143 has the functionalityof gathering all the information that are sensed viz. frequency, powerlevel and location information on the communication channel 149. Alsothe sent information from any other similar remote devices are similarlyreceived and processed to initiate the expected actions.

FIG. 2 is a block diagram illustrating an array of coils focusing theirmagnetic field lines to a target device location in accordance with oneor more embodiments of the present invention. The transmitter resonantphased array 203 has a plurality of coils in the form of an array. Eachof the plurality of the coils is associated with plurality ofcapacitors. The spatial orientation of the plurality of the coils can becontrolled using directional controller 209 in azimuth and elevationdirections.

The controlled power source 205 output is fed to a power divider 206.The PD 206 split the signal power equally into number of output ports.The number of output ports is equal to the number of the tuned circuitsin the array transmitter tuned circuit array 208. The power from theoutput of the power divider 206 is fed to the phase controller 207. Thephase controller 207 adjusts the phase of the signals by exactly thesame amount of the path difference at a distance magnetic focal point215.

The direction controller 209 precisely controls the orientation of thecoils so that the axis of the coils aligns with the line passing throughthe magnetic focal point 215. The line of sight is the line passingalong the coil axis and the magnetic focal point 215. Thus the magneticfield is a maximum in such a line of sight orientation of the coilcompared to any other arbitrary orientations of the coils with respectto the magnetic focal point 215.

Each of the plurality of the coils for e.g. 217 has an associatedcapacitor 219 that is a variable capacitor in some embodiments. Whentuned to the signal power frequency the magnetic field at the magneticfocal point 215 is maximized. Further the phase adjustment by the phasecontroller 207 maximizes the magnetic field pattern at the magneticfocal point 215. This is done by adjusting phase of the magnetic fieldoutput by each of the coils 217. In other embodiments, the lumpedcircuit elements of each element in the array may be one or moreswitchable capacitors, one or more switchable inductors, one or moretransistors, and/or one or more other circuit elements. In otherembodiments, the phase controller 207 produces a plurality of variablephase signals to the plurality of coils such that component switching ofthe associated capacitors 219 may not be required. In still otherembodiments, the capacitors 219 are controlled for resonance purposesbased upon the dynamically adjustable target frequency for maximum powerdelivery to the target device 129.

The magnetic field pattern due to the plurality of the transmitter tunedcircuit array 208 becomes a maximum at the magnetic focal point 215.This results in maximum vector addition of the resonant magnetic patterndue to the individual tuned circuits at the point of the target devicelocation 215 called the magnetic focal point.

At the magnetic focal point 215 the receiver resonant phased array 211is located linking the magnetic field lines and hence receiving thehighest possible power as a result of the coherence or constructiveinterference achieved using controlled power source 205, phasecontroller 207, and the directional controller 209.

An array of tuned coils similar to that of the transmitter tuned circuitarray 208 are tuned to the frequency of the magnetic field on thereceiver resonant phased array 211. The voltages induced and hence thepower received by each of the coils of the receiver resonant phasedarray 211 is combined to increase the efficiency of the method of thepresent invention.

FIG. 3 is a block diagram of illustrating a portion of the phased arrayresonant power transmission system of FIG. 1 that is operable tocalculate the location of the target device based on the receivedinformation to direct a magnetic field pattern in accordance with one ormore embodiments of the present invention. The target device locationreceiver 303 receives the location information sent by the locationfinder 141 of FIG. 1. It extracts the range, elevation, and azimuthinformation of the target device location, for e.g. the magnetic focalpoint 215 of FIG. 2. The coordinate computing device 311 of thedirectional controller 313 uses this information and controls the coilorientation of the transmitter resonant phased array 105 of FIG. 1. Thedirectional controller 313 can precisely control the stepper motors thatcontrol the elevation and the azimuth orientation of the coils at thefiner steps.

In another embodiment of the present invention the target device neednot send its location information. This information is computed by thecoordinate computing device 311 based on the power request signaldirection.

FIG. 4 is a perspective diagram illustrating approximate orientations ofmagnetic fields produced by a phased array resonant power transmissionsystem the resonant coil in the resonant power transmission system andthe receiver resonant phased array magnetically coupled showing thelinking magnetic field lines during the resonant power delivery inaccordance with one or more embodiments of the present invention. In theexemplary configuration of the resonating magnetic field patterncoupling 3 coils 405, 407, and 409 are physically (or operationally inother embodiments) oriented in such way that the line of sight passingalong their axis passes through a common magnetic focal point (215 ofFIG. 2).

As the magnetic field lines are in the closed loop form those magneticfield lines emanating along the coil axis takes longest path to completetheir loop, thus achieving power delivery at the longest distance.

All the magnetic field lines such as 415, 417, and 419 meet at themagnetic focal point 215 of FIG. 2. The interference of all the magneticfield lines 415, 417, and 419 intensifies the magnetic field pattern atthe location of the target device 129 at the point 215 of FIG. 2. Thereceiver resonant phased array 411 intercepts maximum magnetic fieldlines resulting in a maximum power delivery.

FIG. 5 is a block diagram illustrating a receiver resonant phased arrayconnected to (or incorporated with) a target device with each of aplurality of tuned circuits having a coil and a capacitor resonating ata coupled magnetic field frequency in accordance with one or moreembodiments of the present invention. The receiver resonant phased array503 contains an array of receiver tuned circuit array 505, a phasecontroller 507, and a power combiner 509. The receiver resonant phasedarray 503 is associated with a power cord 511. One end of the power cordis attached with the receiver resonant phased array 503 and the otherend fits into the power socket of the target device 513.

The receiver tuned circuit array 505 contains a plurality of the tunedcircuits arranged in the form of a regular array. Each of the tunedcircuits is a combination of a capacitor and a receiving coil. In oneembodiment of the present invention there is a mechanism that can orienteach of the plurality of coils so that there axis aligns with the lineof sight of the transmitting coils of the transmitter resonant phasedarray 203 of FIG. 2.

A power combiner 509 receives all the received and phase compensatedsignals and combine them together. The power combiner has multiple inputports, and an output port. Signals inputted from the plurality of theinput ports are combined and will be outputted in the output port.

The output of the power combiner 509 is connected to the one end of thepower cord 511. The other end of the power cord 511 is plugged into thepower socket of the target device 513. The power cord 511 is animpedance matched (to the ports) power cable with the requiredcharacteristic impedance. It also needs to be lossless for an efficientpower transmission.

FIG. 6 is an illustration of superposition of two signals from twoseparate tuned circuits of the receiver resonant phased array; a similarsuperposition or a spatial constructive magnetic field interference (asvector addition) takes place at the magnetic focal point in accordancewith one or more embodiments of the present invention. The constructiveinterference of either the magnetic field or the voltages is will addmultiple time varying voltage (phasors) or magnetic fields (vectors) ofsame frequency together resulting in a single large amplitude of thesame frequency.

Adding or combining two signals of same frequency the resultant signalwill have its maximum amplitude only when the phases of the two signalsare of same value. The same rule applies for combining multiple signalsof the same frequency. This is because when the phases are same theamplitude of each of the signals can be directly added instead oflooking it as a phasor addition.

The principle of combining multiple signals is similar to the additionof two signals of FIG. 6, whether the addition is on wires or in freespace. Looking at the addition of the fields in the space, it is vectoraddition of multiple field components about a point. The magnitude ofthe two vectors maximizes when the angle between the two vectors tendsto be minimum or zero. Thus the orientation of the plurality of thetransmitter coils is very much of the concern in enhancing theefficiency of the resonant power transmission.

In FIG. 6 two sinusoidal signals of same frequency from two tunedcircuits of the receiver tuned circuit array 505 of FIG. 5 such as tunedcircuit-1 signal 603 and tuned circuit-2 signal 605 are combined in thepower combiner 607. The resulting output of the combination of the twosignals 603 and 605 is the sinusoidal signal 609. The amplitude 611 ofthe signal 603 is ideally the same as the amplitude 613 of the signal605. These signals in general are magnetic field in the space (at themagnetic focal point) or the corresponding voltages at the two inputs ofthe power combiner. The amplitude of the resulting signal 609 is 617will be a maximum of the sum of the two amplitudes viz. 611 and 613,only when the phases of the signals 603 and 605 are the same apart fromtheir frequencies being the same. When the magnetic fields are added theangle between the fields lines also matters during the vector addition.

In order to maximize the received voltage for the battery rechargingthere are few knobs for fine tuning, which will be done automatically inthe present invention by executing some optimization algorithms in theresonant power transmission system 103 of FIG. 1. The control knobs (orparameters) are i) the phases of the signal fed to each of the pluralityof the transmission resonant tuned circuits at the resonant powertransmission system 103, ii) the spatial orientation control of theresonating coils of the transmitter resonant phased array 203 of FIG. 2,iii) the precise placement of the magnetic focal point right over thereceiver resonant phased array 503 of FIG. 5, iv) in one embodiment ofthe present invention, the precise orientation of the receiving tunedcoils are done to link maximum magnetic field for getting maximuminduced voltage across the coil, v) the phase compensation of all thevoltage signals induced across the plurality of the receiver tunedcoils, and finally vi) the quality factor of the entire passivecomponents that are involved in the signal/power transmission path fromthe controlled power source 111 of FIG. 1 till the rechargeable battery133 terminal (of FIG. 1).

FIG. 7 is the system diagram illustrating automatic tripping componentsof a resonant power transmission system when a living body or a movingobject receives a coupling magnetic field in accordance with one or moreembodiments of the present invention. The magnetic field intensity is amaximum in the magnetic focal point 215 of FIG. 2. This is because themagnetic filed from a plurality of the transmitter tuned circuits ofFIG. 2 are interfering constructively. It is not advisable for anyliving object to interfere intentionally or unintentionally close to themagnetic focal point 215 of FIG. 2. This requires a safety mechanismbuilt into the resonant power transmission system 103 of FIG. 1.

The safety mechanism built into the system is in the form of a trippingmechanism when once a moving/living object interferes in the path of themagnetic resonant coupling. This mechanism senses a sudden drop in thereceived power level as it is going to be reported by the target device129 of FIG. 1. An embodiment that incorporates the safety mechanism intothe resonant power transmission system is having an additional modulecalled the power delivery controller 712 which controls the automatictripping circuit 713.

The block of diagram of FIG. 7 has resonant power transmission system703 and a target device 731 connected to a receiver resonant phasedarray 729. The resonant power transmission system 703 has thetransmitter resonant phased array 705 and the communication circuit 715.The transmitter resonant phased array 705 consists of the transmittertuned circuit array 707, the directional controller 708, the phasecontroller 709, the controlled power source 711, and a power deliverycontroller 712. The Power delivery controller 712 further comprises anautomatic tripping circuit 713.

The power delivery controller is a logic circuit that decides amongvarious options. One of the options according to the present ininvention is the decision made during a sudden dropping of the receivedpower level by the target device 731 (129 of FIG. 1 repeated). This canonly happen during a normal course of the resonant power delivery when amoving/living object 749 suddenly comes on the path of power deliveryscattering the magnetic field pattern 725 significantly. There will besignificant scattering when the object comes closer to the magneticfocal point where the magnetic field intensity is high. Also thosepoints around the magnetic focal point are ones where the hazard of highmagnetic field intensity is expected.

Due to the significant field scattering close to the magnetic focalpoint the received power level suddenly drops. This is an indication ofa moving/living object 749 in the path of the resonant power delivery.The drop in the power level is communicated by the target device 731 tothe resonant power transmission system 703. The power deliverycontroller 712 quickly decides to cutoff power delivery for an arbitraryamount of time by actuating the automatic switching circuit 713. Theresonant power transmission system 703 resumes the power delivery whenonce the power delivery controller 712 enables the power delivery.Subsequently the power delivery continues till any further interruptionsor battery charge completion. It is a great concern for any livingobject coming on the path of the power delivery, compared to anynonliving (or moving) objects.

The magnetic field 725 is emanating from the transmitter resonant phasedarray 705 encounters scattering due to the moving/living object 749. Asa result of the scattering most of the magnetic field is deviated indifferent paths not intercepting the receiver resonant phased array 729.The receiver resonant phased array 729 will only receive some minimummagnetic field 751 significantly less than what it would have receivedin the absence of the moving/living object 749 in the path of themagnetic field 725. As a result of the minimum coupling magnetic fieldonly a small fraction of the maximum voltage will be induced in thecoils of the receiver resonant phased array 729 and transmitted on thepower cord 747 into the target device 731.

The communication circuit 715 of the resonant power transmission system703 and target device communication circuit 743 of the target device 731communicate with each other on the communication channel 727. Thecommunication circuit 715 consists of the parameter receiver 717. Theparameter receiver 717 has various other parameter receivers from thetarget device 731 such as frequency selection receiver 719, power levelreceiver 721, and the target device location receiver 723.

The target device 731 is indicated to have at least the power chargingcircuit 733 (131 of FIG. 1 repeated), the power level sensor 741, andthe target device communication circuit 743. The power charging circuit733 has the battery charging circuit 735 and the rechargeable battery737.

FIG. 8 is a flowchart illustrating operations 801 performed by theresonant power transmission system of FIG. 1 during resonant powerdelivery operations in accordance with one or more embodiments of thepresent invention. Starting at the block 803 the resonant powertransmission system sends the beacon signal at the next block 805. Inresponse to this beacon signal soliciting the resonant power deliveryservice the target devices within the range of the resonant powertransmission system sends the power request.

In response to the request sent by the target device, the resonant powertransmission system 103 of FIG. 1 seeks assertion of the target deviceauthentication at the block 807. In response to this the target devicesends its identity and its subscription details to the resonant powertransmission system 103 of FIG. 1. At the next block 809 the resonantpower transmission system authenticates the target device. In responseto the authentication, the target device sends its location informationin the form of the GPS coordinates of its location in one embodiment ofthe present invention. The resonant power transmission system 103 ofFIG. 1 receives the target device information in the next block 811. Inanother embodiment of the present invention the resonant powertransmission system computes the location of the target device based onthe power request signal arrival direction information.

In response to receiving the target device location information sent bythe target device, the resonant power transmission system steers themagnetic field pattern in the direction of the target device and startsdelivering the resonant power to the target device at the block 813. Theresonant power transmission system 103 of FIG. 1 continues to deliveringthe resonant power. During the process of resonant power delivery theresonant power transmission system 103 keeps monitoring themoving/living objects closed to the magnetic focal point and in case ofany moving/living objects the resonant power transmission systemcontrols a tripping mechanism to temporarily cutoff the power supply atthe block 815. The activation of the tripping circuit is done based onthe power level information sent by the target device at the regularinterval. After an arbitrary period of time the power transmission isresumed at the next block 816.

The resonant power transmission system 103 of FIG. 1 continues tomonitor the charging status of the rechargeable battery of the targetdevice by receiving the charge status information sent by the targetdevice at the block 817. This is required to cutoff the powertransmission once the battery is fully charged. Subsequently the targetdevice sends the total time of the charging operation which will be usedto update the billing information. This is done at the next block 819.The process of the resonant power delivery ends after a successfulbattery charging operation at the last block 821.

FIG. 9 is a flowchart illustrating operations 901 performed by a powerdelivery controller of the resonant power transmission system of FIG. 1when a moving object interferes on the path of the resonant magneticpattern in accordance with one or more embodiments of the presentinvention. Starting the block 903 the power delivery controller 712 ofFIG. 7 enables the power delivery to the target device at the block 905.The power delivery is initiated subsequently by the resonant powertransmission system 103 of FIG. 1. In response to the power delivered bythe resonant power transmission system 103 the target device sends 907the received power level information back to the resonant powertransmission system 103 of FIG. 1.

During the initiation of the power delivery, the receiving power willnot be the maximum power level as the magnetic field maximization isrequired using the coils direction orientation, and the phasecontrolling of the signal along the path of power delivery. Graduallyover a small period of time, the received power level reaches its steadystate maximum value.

At the decision block 909 the power delivery controller tests whetherthe resonant power delivery is done at the steady state value. If thetest returns false at the block 909, the power delivery controller goesto the block 929, where it will enable the power level by a fineradjustments using the signal amplifier gain control and by the phasecontrolling of signal phase. Operation returns to block 927 where itfine tunes or optimally orients the transmitter resonant phased arraycoils to maximize the power delivered to the magnetic focal point 215 ofthe FIG. 2. From the block 927 the power delivery controller 712 goesback to the state 907.

If the tests in the decision block 909 returns true, the power deliverycontroller goes to the state 913 continuing to enable the resonant powerdelivery. Subsequently the power delivery controller receives the powerlevel information sent by the target device at the block 915. At thenext decision block 917 it is tested to see whether the power leveldropped significantly.

If the test performed at the block 917 returns true the power deliverycontroller 712 actuate the automatic tripping circuit at the block 919,and subsequently at the block 921 the power delivery controller enters apredetermined amount of wait state and goes back to enable the powerdelivery at the block 913.

If the test in the decision block 917 returns false then at the nextdecision block 923 the power delivery controller tests whether thebattery is charged fully. If the test returns true the process of powerdelivery is ended in the last block 925, else the power deliverycontroller 712 control goes back to the previous block 913 to continueenabling the power delivery.

As one of ordinary skill in the art will appreciate, the terms “operablycoupled” and “communicatively coupled,” as may be used herein, includedirect coupling and indirect coupling via another component, element,circuit, or module where, for indirect coupling, the interveningcomponent, element, circuit, or module does not modify the informationof a signal but may adjust its current level, voltage level, and/orpower level. As one of ordinary skill in the art will also appreciate,inferred coupling (i.e., where one element is coupled to another elementby inference) includes direct and indirect coupling between two elementsin the same manner as “operably coupled” and “communicatively coupled.”

The present invention has also been described above with the aid ofmethod steps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention.

The present invention has been described above with the aid offunctional building blocks illustrating the performance of certainsignificant functions. The boundaries of these functional buildingblocks have been arbitrarily defined for convenience of description.Alternate boundaries could be defined as long as the certain significantfunctions are appropriately performed. Similarly, flow diagram blocksmay also have been arbitrarily defined herein to illustrate certainsignificant functionality. To the extent used, the flow diagram blockboundaries and sequence could have been defined otherwise and stillperform the certain significant functionality. Such alternatedefinitions of both functional building blocks and flow diagram blocksand sequences are thus within the scope and spirit of the claimedinvention.

One of average skill in the art will also recognize that the functionalbuilding blocks, and other illustrative blocks, modules and componentsherein, can be implemented as illustrated or by discrete components,application specific integrated circuits, processors executingappropriate software and the like or any combination thereof.

Moreover, although described in detail for purposes of clarity andunderstanding by way of the aforementioned embodiments, the presentinvention is not limited to such embodiments. It will be obvious to oneof average skill in the art that various changes and modifications maybe practiced within the spirit and scope of the invention, as limitedonly by the scope of the appended claims.

1. A resonant power transmission system for wirelessly deliveringelectric power to a target device, the resonant power transmissionsystem comprising: a power source operable to source alternating currentpower at a target frequency; a plurality of transmitting elements, eachoperable to produce a non-radiated magnetic field, the plurality oftransmitting elements operable to produce a composite non-radiatedmagnetic field; and control circuitry operable to control the pluralityof transmitting elements to direct the composite non-radiated magneticfield toward the target device.
 2. The resonant power transmissionsystem of claim 1: further comprising a plurality of transmitter circuitelements operable to couple the alternating current power to theplurality of transmitting elements; and the control circuitry furtheroperable to control the plurality of transmitter circuit elements todirect the composite non-radiated magnetic field toward the targetdevice.
 3. The resonant power transmission system of claim 2, wherein atleast some of the plurality of transmitter circuit elements compriselumped circuit elements.
 4. The resonant power transmission system ofclaim 1, further comprising a communication circuit operable tocommunicate with the target device.
 5. The resonant power transmissionsystem of claim 1, wherein: the plurality of transmitting elementscomprise a plurality of coils; and the control circuitry is operable toindividually control phase of the non-radiated magnetic fields producedby the plurality of transmitting elements.
 6. The resonant powertransmission system of claim 1, wherein the control circuitry isoperable to receive feedback from the target device via thecommunication circuitry that is used to direct the compositenon-radiated magnetic field.
 7. The resonant power transmission systemof claim 1, wherein the plurality of transmitting elements are arrangedin an array.
 8. The resonant power transmission system of claim 1,further comprising a target device authentication module forauthentication of the target device for wireless power delivery.
 9. Theresonant power transmission system of claim 1, further comprising afrequency selection controller for selecting the target frequency. 10.The resonant power transmission system of claim 1, further comprising abeacon module operable to transmit via the communication circuit abeacon regarding wireless power delivery.
 11. The resonant powertransmission system of claim 1, wherein the control circuitry is furtheroperable to dynamically select the target frequency.
 12. A method forwirelessly delivering electric power to a target device, the methodcomprising: sourcing alternating current power at a target frequency;coupling the alternating current power to a plurality of transmittingelements to produce a non-radiated magnetic field by each of theplurality of transmitting elements, the plurality of non-radiatedmagnetic fields producing a composite non-radiated magnetic field; andcontrolling the non-radiated magnetic fields produced by the pluralityof transmitting elements to direct the composite non-radiated magneticfield toward the target device.
 13. The method of claim 12, furthercomprising communicating with the target device.
 14. The method of claim12, wherein controlling the non-radiated magnetic fields produced by theplurality of transmitting elements to direct the composite non-radiatedmagnetic field toward the target device comprises individuallycontrolling phase of alternating current power provided to at least someof the plurality of transmitting elements.
 15. The method of claim 12,wherein controlling the non-radiated magnetic fields produced by theplurality of transmitting elements to direct the composite non-radiatedmagnetic field toward the target device comprises controlling aplurality of transmitter tuned circuit elements respectively associatedwith the plurality of transmitting elements.
 16. The method of claim 15,wherein controlling a plurality of transmitter tuned circuit elementsrespectively associated with the plurality of transmitting elementscomprises altering lumped tuning element settings of the plurality oftransmitter tuned circuit elements.
 17. The method of claim 12, furthercomprising: receiving feedback from the target device; and using thefeedback to direct the composite non-radiated magnetic field.
 18. Themethod of claim 12, further comprising authenticating the target devicefor wireless power delivery.
 19. The method of claim 12, selecting thetarget frequency to facilitate transfer of power.
 20. The method ofclaim 19, wherein selecting the target frequency comprises selecting thetarget frequency based upon feedback received from the target device.21. The method of claim 12, further comprising wirelessly transmitting abeacon regarding wireless power delivery.
 22. The method of claim 12,wherein controlling the non-radiated magnetic fields produced by theplurality of transmitting elements to direct the composite non-radiatedmagnetic field toward the target device comprises physically controllingorientation of the plurality of transmitting elements.